This section is intended to provide a background or context to the invention recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Hydraulic machines typically include a hydraulic control system for routing hydraulic fluid to one or more components of the machine. The hydraulic control system routes pressurized hydraulic fluid to each component, providing a force (i.e., hydraulic power) to move or otherwise control the component. Hydraulic excavators, for instance, typically include a boom that is raised and lowered by pressurized hydraulic fluid routed through a hydraulic control system, such as to move an attached bucket (e.g., dipper, shovel, etc.) for digging. The pressurized fluid is often provided by a hydraulic pump and routed to hydraulic cylinders that are coupled to the boom and configured to extend or retract in order to raise and/or lower the boom. In an industrial setting such as a mining or construction site, the hydraulic excavator may be required to raise and lower the boom repeatedly, requiring pressurized fluid to be pumped to the hydraulic cylinders each time the boom is raised or lowered. The hydraulic pump is often powered by a motor or engine, which may require fuel or other energy in order to power the pump.
Some hydraulic machines may include control systems or circuits having a regeneration function intended to supply fluid to a hydraulic component without discharging additional fluid from the hydraulic pump. An example of such a control system can be found in U.S. Pat. No. 7,337,807, issued Mar. 4, 2008, for “Hydraulic Control Valve with Regeneration Function,” which discloses a hydraulic control valve “capable of maintaining the pressure in a regeneration fluid passage” despite changes in the discharge flow rate of the hydraulic pump. However, the disclosed control valve includes a regeneration valve that is installed within the control valve, resulting in significant design and installation costs in order to implement the regeneration function into existing machines. In addition, the disclosed control valve requires additional components in order to implement the regeneration function, including a regeneration fluid passage for storing a supply of regeneration fluid and a separate return line connected to the hydraulic tank. The additional components require additional maintenance, replacement and other costs, and require additional space within the machine for routing the components.